Electronic devices provided with touch panels with which the screens of display apparatuses are covered have been developed in recent years. The electronic devices include personal digital assistants (PDAs), portable game machines, and mobile phones. A user of such an electronic device provided with a touch panel presses a portion of the touch panel, which is over an image displayed on the screen, with his/her finger or a pen. The user is capable of operating the image corresponding to the pressed portion. When a pointer (cursor) is displayed on the screen, the user first presses a portion where the pointer is displayed with his/her finger or the like. Then, the user slides his/her finger on the touch panel. The user is capable of moving the pointer. The provision of the touch panel allows the user to instinctively operate the electronic device. In addition, there is no need to provide, for example, selection buttons used to select an image and operation buttons used to move the pointer in the electronic device provided with the touch panel. Accordingly, it is possible to save the spaces where the buttons are provided and to increase the screen in size in the electronic device provided with the touch panel.
Electronic devices including two screens that are covered with touch panels have also been developed. In such an electronic device, for example, two display apparatuses are connected with a hinge mechanism. The electronic device may be collapsed in a state where the two screens are opposed to each other. This configuration may prevent the electronic device from increasing in size. When the electronic device is used by a user, the electronic device changes from the state in which the electronic device is collapsed to a state in which the two screens are arranged in parallel with the hinge mechanism provided therebetween. The provision of the two screens allows the electronic device to display a larger amount of information, compared with the case in which one screen is provided.
It is necessary for the electronic device including the two screens covered with the touch panels to determine whether operations performed with the touch panels are associated with each other. An operation performed with each touch panel, for example, by touch of user (e.g., finger) and/or a device/utensil (e.g., stylus, pen, etc.), is hereinafter referred to as a touch operation. For example, when the user attempts to move a pointer displayed on one screen to the other screen, the user is required to release his/her finger on the pointer from the touch panel with which the one screen is covered because the hinge mechanism is provided between the two touch panels. In this case, it is necessary for the electronic device to correctly determine whether the movement operation of the pointer by the user is terminated or whether the movement operation continues into the touch operation on the other touch panel.
A typical electronic device provided with two screens in related art determines that the touch operation on one touch panel continues into the touch operation on the other touch panel if the time period between the time when the touch operation on the one touch panel is terminated and the time when the touch operation on the other touch panel is started is within a certain time. Japanese Unexamined Patent Application Publication No. 11-73269 discloses a method of determining that the touch operation on one touch panel continues into the touch operation on the other touch panel if the touch operation on the one touch panel is terminated within a certain area. The technology disclosed in Japanese Unexamined Patent Application Publication No. 11-73269 determines the start position of the touch operation on the other touch panel, which corresponds to the end position of the touch operation on the one touch panel, and displays the determined position on the screen covered with the other touch panel to notify the user of the position to be pressed. In addition, Japanese Unexamined Patent Application Publication No. 2000-242393 discloses a method of determining that the touch operation on one touch panel continues into the touch operation on the other touch panel if a position set on the other touch panel is pressed when the touch operation on the other touch panel is started after the touch panel on the one touch panel is terminated.